Verified answer

An augmented chord is built with the root, plus 4 half steps, plus 4 half steps

E G# B# D(if you want to add the 7th - Eaug7)

You don't have to use a whole tone scale to improvise over an augmented chord - you can use mixolydian, or a diminished scale.

E G# B# (enharmonic with C)

Depending upon the context, you do not need a whole tone scale.

An augmented chord is often also used as a substitution for the V chord - replacing it with V+ ... giving it a contrary half-step movement when it resolves to I or i.

In this case, any scale with a b6 (like the minor scales) would work.

For instance, if you have the appearance of an E+ in the key of Am ... the C natural (spelled as a B# in the E+ chord) will function well as a featured note in any sort of A tonality.